Spin-draw Process Research Articles

Improvement of the Mechanical Properties of Poly(Glycolic Acid) Fibers Through Control of Molecular Entanglements in the Melt Spinning Process

To improve the mechanical properties of poly(glycolic acid) (PGA) fibers prepared by the direct spin-drawing process, the concept of “melt structure control” was introduced. A heating chamber was installed in the vicinity of the spinning head and a low take-up velocity in the melt spinning process was adopted to reduce the Deborah number in the spin-line. As a result, improvement of the toughness of as-spun fibers prepared by the melt-spinning process was accomplished, and the drawn fibers of high-strength and high-toughness were obtained by applying an additional in-line drawing process. Entanglement density reduction in the melt spinning process was found to be suppressed by installing a heating chamber as well as by lowering the take-up velocity. Through the matching of the true stress versus true strain curves of in-line drawn fibers by shifting the curves along the true-strain axis, the network draw ratio of the drawn fibers was estimated and the master curves for individual spinning conditions were prepared. The master curves were found to show steeper increases from lower true-strains for the lower Deborah number conditions, whereas the increases in birefringence and strength of the drawn fibers proceeded from the lower network draw ratios.

Effects of Spinning Conditions on Properties of Polyester Yarn Prepared using an Ultra-high-speed Melt Spinning Technique Equipped with a Steam Chamber

In this study, the effects of the various parameters of spinning and drawing processes on the properties of polyester full drawn yarn (FDY) prepared by steam processing during high-speed spinning were investigated using several techniques. The wet shrinkage ratio of the FDY was able to be manipulated by controlling the temperature and draw ratio. The FDY made using the steam high speed spinning technique exhibited identical properties (such as tenacity, elongation, and wet shrinkage ratio) to that of regular FDY, made using the spin-draw process. FDY prepared using the steam process during high-speed spinning showed excellent dyeability. The dye pick-up of the polyester yarn spun at high-speed spinning was found to be improved when dyed under an atmospheric pressure of <TEX>$100^{\circ}C$</TEX>. This result was the same as regular FDY dyed under a high pressure of <TEX>$130^{\circ}C$</TEX>.

Influence of fiber-like nanofillers on the rheological, mechanical, thermal and fire properties of polypropylene: An application to multifilament yarn

Polypropylene and polypropylene grafted maleic anhydride based composites with modified and non-modified carbon nanotubes and sepiolite were prepared by melt extrusion. Their thermal, rheological, and dynamic mechanical properties were evaluated. Multifilament yarns were obtained from the composites by spin-drawing process and their mechanical properties were measured. Knitted fabrics from the multifilament yarns were characterized by cone calorimetry. The best interaction was obtained for polypropylene/carbon nanotubes and polypropylene/polypropylene grafted maleic anhydride/sepiolite composites, as was confirmed by the increasing on the elastic modulus and thermal resistance. Nanofillers changed the thermal decomposition profiles compared to bare polypropylene. Knitted structures containing sepiolite decrease the maximum of heat release rate in comparison with unfilled samples.

Internal structure and physical properties of thermotropic liquid crystal polymer/poly(ethylene 2,6-naphthalate) composite fibers

Thermotropic liquid crystal polymer (TLCP)/poly(ethylene 2,6-naphthalate) (PEN) composites and their fibers were prepared by using melt compounding and spin-draw process. Thereafter, they were additionally drawn by various drawing methods. As TLCP contents increased, melt flow index was increased and shear viscosity was decreased because TLCP fibril structure of rigid backbones was formed during melt compounding. Molecular orientation and crystalline structure of the TLCP/PEN composite fibers were improved as a function of draw ratio and the heat–laser drawing method gave synergic effects on internal structure of the TLCP/PEN composite fibers. Thermal stability of the TLCP/PEN composite fiber was improved significantly by incorporating small amount of TLCPs.

Numerical simulation of the spin-draw process of poly(ethylene terephthalate) fibers

Numerical simulation for the calculation of the profile developments of the spin-draw process in the melt spinning of poly(ethylene terephthalate) was performed. Both spinning and drawing profiles were analyzed and included the structure development of birefringence and crystallinity in the draw line. By applying a simple model describing the continuous drawing process, we made it possible to simulate the spin-draw process. The strain rate of the spinline had a broad distribution, and that of the draw line had a narrower peak. The calculated birefringence ranged from 0.176 to 0.192 and the crystallinity ranged from 0.37 to 0.44 with draw ratio. The birefringence profile had a similar pattern as the stress profile, and the crystallinity gently increased along the draw line more than the birefringence did. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2522–2527, 2007

Structure and Drawability of Polypropylene Fibers in the Direct Spin Draw Process Equipped with the Cooling Take-up Roll

In the field of nylon and polyester fibers, there has been a tendency in recent years for the Direct Spin Draw (DSD) process to become the mainstream technology. However, in the case of Polypropylene (PP), fibers with high tenacity could not be obtained using the DSD process because PP fibers could not be drawn to high draw ratio. To solve this problem, a new DSD (I-DSD) process was developed. In this process, a contact-type cooling take-up roll was installed after the melt spinning stage and an as-spun fiber was drawn after it was force cooled. It was possible to effectively control the crystallinity of as-spun fibers and increase the maximum draw ratio of the fiber to as high as 9 even when drawing was carried out on an in-line basis. This high draw ratio was almost equal to that obtained in the Offline Drawing (OFD) process. In addition, it was found that as-spun fiber with lower crystallinity had a higher maximum draw ratio. A negative correlation coefficient between the crystallinity and the maximum draw ratio of as-spun fiber was found for the I-DSD process.

Structure and Mechanical Properties of Polypropylene Fiber in the Direct Spin Draw Process Equipped with the Cooling Take-up Roll

In the field of nylon and polyester fibers, there has been a tendency in recent years for the Direct Spin Draw (DSD) process to become the mainstream technology. However, in the case of Polypropylene (PP), fibers with high tensile strength could not be obtained using the DSD process because as-spun fibers could not be drawn to high draw ratio.To solve this problem, a new DSD (I-DSD) process was developed. In a previous paper, studies on the effect of installation of a cooling take-up roll on the structure and drawability of as-spun fibers were carried out. In this paper, the structure of fibers obtained in the following three processes was examined: (1) the I-DSD process, (2) the conventional-type DSD (C-DSD) process and (3) the offline drawing (OFD) process in which drawing is carried out on an offline basis. There was a large difference in the structure of fibers drawn to the same draw ratio in the C-DSD process and the other two processes. The fiber obtained by the C-DSD process was found to have higher crystallinity and higher birefringence values compared with the other two. On the other hand, the highest melting point of fiber was obtained in the OFD process, followed by the I-DSD process, and then by the C-DSD process. It was found that a fiber with a lower melting point had a shorter “long period”.In addition, the tensile strength of fiber obtained by the C-DSD process was the highest among the fibers obtained by the three processes when compared at the same draw ratio. However, because the draw ratio could only be increased to about 3-4, its tensile strength could only be raised to around 0.30GPa. On the contrary, the draw ratio of fiber obtained in the I-DSD process, as in the OFD process, could be increased to about 9, so that it was possible to obtain fibers whose tensile strength was high or about 0.51GPa.

Melt spinnable spandex fibers from segmented copolyetheresteraramids

AbstractSpandex fibers were obtained by melt spinning segmented copolyetheresteramides with crystallizable aromatic diamide units of uniform length and poly(tetramethyleneoxide) segments. The aramid content was varied from 3 to 22 wt %, and the molecular weight of the polyether segment ranged from 1000 to 9000 g/mol. The influence of the spinning and drawing conditions on the fiber properties was investigated. The aromatic diamide units crystallize very fast. This made the melt spinning of the polymers easy. The aramide units were also found to be very effective in increasing the modulus. For a high elasticity a low aramid content was beneficial, and with a few percent a good elastic behavior is obtained. Orientation by drawing or a spin drawing process improves the elastic behavior. The elastic properties are compared to the values of commercial spandex fibers. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 82: 2194–2203, 2001

Biodegradable fibres spun from poly(lactide) generated by reactive extrusion

Poly(lactide) (PLA) was spun both in a high speed spinning process with take-up velocities of 1000–5000 m min −1 and in a spin drawing process at draw ratios of 4–6. The effect of the melt spinning conditions on the development of the structural hierarchy in the fibres and the relations to the textile physical properties were investigated. The PLA fibres were characterised with regard to the degree of crystallinity by DSC and WAXS, the orientation by WAXS and birefringence, and the stress–strain behaviour. The maximum physical break stress and the E-modulus observed in the spin drawn fibres were about 490 MPa and 6.3 GPa, respectively, at an elongation at break of 30%. The PLA was a copolymer of l-lactide (92 wt.%) and meso-lactide (8 wt.%) and was generated by reactive extrusion polymerisation. The PLA virgin pellets were analysed regarding their degradation during the spinning processes. Their thermal and rheological properties were determined by DSC and dynamic rheological measurements, respectively, to derive suitable parameters for the melt spinning processes.

High‐performance PET fibers via liquid isothermal bath high‐speed spinning: Fiber properties and structure resulting from threadline modification and posttreatment

Poly(ethylene terephthalate) fibers with improved mechanical properties and dimensional stability were spun via controlled threadline dynamics by a liquid isothermal bath (LIB) spinning process, followed by postdrawing and annealing. Control fibers were made by unperturbed spinning and posttreatment similar to a traditional spin—draw process. The two sets of as-spun fibers were spun at take-up speed in the range of 2000–5000 m/min. Fiber properties of the as-spun fibers and posttreated fibers of each process were compared. Two commercial tire cords, i.e., conventional tire cord and low shrinkage tire cord, were also included. Unlike unperturbed spinning, the LIB as-spun fibers show unique structural properties of high amorphous orientation, low crystallinity, high strength, and high initial modulus. Moreover, noncrystalline chains are further extended during posttreatment. The posttreated LIB fibers exhibit mechanical properties with tenacity higher than approximately 9 g/d, initial modulus higher than 120 g/d, and ultimate elongation less than approximately 10%. They also demonstrate superior dimensional stability with thermal shrinkage less than 6% and LASE-5 higher than 5 g/d. The overall properties are not obtainable by either the traditional spin—draw process or any modified process that produces low shrinkage tire cord. Unlike the case for unperturbed fibers, the mechanical properties of the posttreated LIB fibers demonstrate a strong/dependency on the birefringence of their respective as-spun fibers. There are at least three significant pieces of evidence that strongly indicate the existence of a third phase, referred to as the taut—tie noncrystalline phase (TTNC), in addition to the traditional two-phase model, i.e., crystalline and random amorphous phases. A unique feature involving a high fraction of taut—tie noncrystalline phase (TTNC %) in the LIB as-spun and the posttreated fibers is also found and which is, in fact, achieved neither by the traditional spin—draw nor the commercial tire cord processes. Further, different from the posttreated unperturbed fibers, the posttreated LIB fibers have an enhanced fraction of taut—tie noncrystalline chains with shorter length, which is believed to be one of the important factors leading to the superior mechanical properties and excellent dimensional stability achieved. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2441–2455, 1997

High-performance PET fibers via liquid isothermal bath high-speed spinning: Fiber properties and structure resulting from threadline modification and posttreatment

Poly(ethylene terephthalate) fibers with improved mechanical properties and dimensional stability were spun via controlled threadline dynamics by a liquid isothermal bath (LIB) spinning process, followed by postdrawing and annealing. Control fibers were made by unperturbed spinning and posttreatment similar to a traditional spin—draw process. The two sets of as-spun fibers were spun at take-up speed in the range of 2000–5000 m/min. Fiber properties of the as-spun fibers and posttreated fibers of each process were compared. Two commercial tire cords, i.e., conventional tire cord and low shrinkage tire cord, were also included. Unlike unperturbed spinning, the LIB as-spun fibers show unique structural properties of high amorphous orientation, low crystallinity, high strength, and high initial modulus. Moreover, noncrystalline chains are further extended during posttreatment. The posttreated LIB fibers exhibit mechanical properties with tenacity higher than approximately 9 g/d, initial modulus higher than 120 g/d, and ultimate elongation less than approximately 10%. They also demonstrate superior dimensional stability with thermal shrinkage less than 6% and LASE-5 higher than 5 g/d. The overall properties are not obtainable by either the traditional spin—draw process or any modified process that produces low shrinkage tire cord. Unlike the case for unperturbed fibers, the mechanical properties of the posttreated LIB fibers demonstrate a strong/dependency on the birefringence of their respective as-spun fibers. There are at least three significant pieces of evidence that strongly indicate the existence of a third phase, referred to as the taut—tie noncrystalline phase (TTNC), in addition to the traditional two-phase model, i.e., crystalline and random amorphous phases. A unique feature involving a high fraction of taut—tie noncrystalline phase (TTNC %) in the LIB as-spun and the posttreated fibers is also found and which is, in fact, achieved neither by the traditional spin—draw nor the commercial tire cord processes. Further, different from the posttreated unperturbed fibers, the posttreated LIB fibers have an enhanced fraction of taut—tie noncrystalline chains with shorter length, which is believed to be one of the important factors leading to the superior mechanical properties and excellent dimensional stability achieved. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2441–2455, 1997

High performance PET fibre properties achieved at high speed using a combination of threadline modification and traditional post treatment

A process was investigated for producing high modulus, high strength, dimensionally stable poly(ethylene terephthalate) (PET) filament by combination of threadline modification and post drawing techniques. Unlike traditional commercial processes for the production of PET filament yarn, the present process uses a liquid isothermal bath to develop an extremely high level of tension in the threadline. This results in extremely high amorphous orientation and low crystallinity in the as-spun fibres, with good mechanical properties, similar to those found in products produced using a commercial spin-draw process. The oriented amorphous structure produced directly by such a modified spinning process can be further oriented by a subsequent hot-drawing operation, resulting in a final PET filament product which possesses ultra-high birefringence ( Δn > 0.23) and excellent mechanical properties. The tenacity, elongation, and initial modulus ( T/E/M) are, respectively, in the range of 9.5–10.7 g d −1, 6–9%, and 130–150 g d −1. Experimental filaments also exhibit excellent resistance to yielding within the range of small strain, with tensile stress values as high as 5–7 g d −1 being observed at 5% elongation. This superior balance of properties, high modulus, high tenacity and high dimensional stability, is unprecedented in conventional commercial processes for the production of PET filament.

Hot Drawing Behavior of High Speed Melt Spinning. Part 1. Fundamental analysis of hot drawing in spinline and introduction of basic equations for simulation.

In a polymer processing system using Spinline Heating Spinning (SHS) technique, the conventional drawing process can be omitted. The SHS process is characterized by the presence of a heating device located between the spinneret point and the take-up point. Drawing was conducted in the heating zone at lower spinning tension and higher temperature in comparison with the conventional spin-draw process. Unlike the conventional drawing system, the draw ratio can be regarded as an out-put variable in this process. Along with the experimental clarification of the behavior of SHS, the basic equations including the drawing behavior in the heating device were introduced for the numerical analysis. The agreement between calculated and experimental results for various take-up velocities and heating conditions were sufficient The physical properties of fibers obtained by SHS were intermediate between those of high-speed spun fibers and conventionally drawn fibers. The structural characteristics of SHS fibers were also clarified.